TUTORIAL- Rotation Center/Modifier

[im42n8 Profile Private messageWebsite]

Picture Slide.

This tutorial describes how to create a slide in the demo given in the link below (it's on slide number 7. Note that each effect in the demo is created on a single slide ... should make it easy to jump ahead to the specific slide.).

In this slide are two images, one on top of the other. They rotate together slowly, edge to edge (on the same apparent rotation point) until the top image appears to slide off and disappear off screen. Freed from its weight, the remaining image springs to screen center, realigned horizontally ... and then scurries off screen as well.

http://www.photodex.com/sharing/viewsho ... alb=148411
(go to the 7th slide)

Demonstrates: Use of the rotation center & a rotation modifier

I started out with two images that were sized at 4672x3104 pixels. They were fit to safe zone and sized to a zoom of 50%. The slide time is set to 8s. The left transition is 1s and the right transition is 1.5s. I used a cross-fade transition effect.

Layers 1 keyframes at: 0 (1), 1(2), 2.143 (3), 4.429 (4), 9 (5), and 10.5s (6).
Layer 2 keyframes at: 0 (1), 1(2), 2.143 (3), 4.429 (4), 6.26 (5), 7.446 (6), 7.877 (7), 9.330 (8) and 10.5s (6).

Rotation Center: set KF2 to last kf at -50,50. All KF’s in between are auto)
Smoothing: set to 0, all keyframes

Layer 1
KF1. Pan-x: 75, Pan-y: 22. Rotate: -720
KF2. Pan-x: 0, Pan-y: auto. Rotate: 0.
KF3. Pan-x and Pan-y: auto. Rotate: 0
KF4. Pan-x:0; Pan-y: -22. Rotate: 10 (This is the manual rotate. The other layer uses a modifier).
KF5. Pan-x: 92; Pan-y: 7. Rotate: auto
KF6. Pan-x: 92; Pan-y: 7 Rotate: 10.
Note: in this case you could use a modifier of value=0.001 on kf2 and kf3 and of value=2.8 on kf4. Check the use for all keyframes box. The value on kf2 and kf3 removed kf4's influence from them. In the case used above, I was just comparing the operation of the two in this case. At any rate, you can tell the difference in application between using a rotation and using a modifier to accomplish effectively the same task!

Layer 2.
KF1. Pan-x: -75, Pan-y: -50. Rotate: 360 (just a flair for coming onto the screen!)
KF2. Pan-x: 0, Pan-y: 23. Rotate: 0.
KF3. Pan-x and Pan-y: auto. Rotate: auto
KF4. Pan-x:0; Pan-y: auto. Rotate: auto
KF5. Pan-x: auto; Pan-y: 23. Rotate: auto
KF6. Pan-x: 0; Pan-y: 0 Rotate: auto
KF7. Pan-x: 0; Pan-y: 0 Rotate: auto.
KF8. Pan-x: 75; Pan-y: 0 Rotate: auto.
KF9. Pan-x: 75; Pan-y: 21 Rotate: 0

Modifer on kf4 and kf5 is a constant of +2.8. Uncheck Use for all keyframes
Note:f you did not uncheck Use for all keyframes, you would need to place a constant 0.001 (this will get rounded to a value of 0.00 by the program) onto kf3 and kf6 to return the rotation back to 0.

======================================

ROTATION. A modifier constant added to a rotation is a % of 360 degrees. Constants are added at minimum value of 0.01 or greater. That means that changes are made in increments of 0.036 degrees.

ROTATION CENTER. Like a pan, this is a reference from the layer center. The middle point of the layer, both horizontally and vertically, is the default rotation center of a layer. So, in a layer, a rotation center that is specified to have an x-value of -50 and a y-value of 50 means the lower left corner (50% to the left if the left edge of the image. 50% to the right is the right edge of the image. And, 50% down – a positive 50 – is the bottom edge of the image and -50 is the top edge of the image.). Therefore, if a constant of 50 is entered for the rotation center-x, the image will rotate at a point located on the left edge of the image and halfway down from the top of the image (assuming no other changes to the default rotation center has been made).

So a rotation value of 2.8 is (2.8/100)*360=10.08 degrees (or 10 degrees ...!).

To determine the point to the right that you’d need to ensure a good appearance of a slide, you could use trigonometry. Or, you could use the tried and true method of hunt and peck until you find a position off screen that gives you what you need to give you a good appearance of a sliding off the lower image!

For the trigonometry method. I chose a point that would ensure the layer was completely off the screen. For some reason I chose 92. Going from 0 to 92 gives me a length of 92. My rotation is 10 degrees. I need to know at what point DOWN I need to go to get a value. The tangent of 10 degrees is the value of 92/DOWN. So, my equation is DOWN = 92 Tan10. A handy dandy calculator with trig functions (or use a spreadsheet program) gives me a value of 16.22. Now, if I multiply 16.22 by 16/9 (the screen ratio) I get 28.84. Since the layer is located at pan-y = -22, the actual DOWN value that I need is -22+28.84 which equals 6.84 or 7 (rounded up).

Had I used 100 as a base instead of 92, it'd be 100*tan10 =17.63. Making the ratio adjustment as above, I get 17.63*16/9=31.35. Then 31.35 + (-22) gives me a DOWN value of 9.32. So, my pan-y value would 9.

.....|\ ...... Assume the angle of rotation at the apex of this triangle (call it angle x), is from the vertical.
.....|..\ ....."a" represents the amount we want to move the layer off screen. "b" represents the
..a..|...\ ....amount "down" we need for a good looking slide off the lower layer.
.....|___\ ... Then tan x = opposite/adjacent = b/a and so, b = a * tan x
.......b

I found it surprising that an adjustment for the screen ratio was necessary to get the correct "drop." But, it is necessary to consider! So, for a vertical drop you need to multiply "b" by the screen ratio (in this case it was 16/9 ... had all the calculations been pan-y oriented instead, you would probably need 9/16 instead to get your correct pan-x value) and then add the pan-y value appropriately. This gives you the correct screen coordinate for your pan-y value.

Dale

[rkligman Profile Private messageWebsite]

It would appear that you are the Rotation Center guru. Nice effects.

[nannybear Profile Private messageWebsite]

I saw this in that show I just watched and think it is a great effect!! Cheers Jan

[kayeb Profile Private message]

Thanks Dale for creating this tutorial. Very nice effects. You definitely understand and know how to use the modifers and rotation effects. It is way beyond my comprehension right now. I still don't have masking down yet.

Kaye

[Cliff.Thomas Profile Private message]

Dale

Thanks for the info.

This is the type of technical info I need so that I can begain understand how these things work together.

I found it surprising that an adjustment for the screen ratio was necessary to get the correct drop. But, it is necessary to consider! So, for a vertical drop you need to multiply "b" by the screen ratio (in this case it was 16/9 ... had all the calculations been pan-y oriented instead, you would probably need 9/16 instead to get your correct pan-x value) and the add the pan-y value appropriately. This will give you the correct screen coordinate to use for your pan-y value.

You've obviously put a lot of effort into this. That one was new to me.


Cliff

[jdgouk Profile Private message]

Dale,
Informative and interesting tutorial and show.
Thanks for the post.

Jason

[twodoor55 Profile Private message]

Dale, thanks for taking the time to give us all a math lesson. I was trying to figure out how these worked and you explained it in great detail. Is there a pdf so I can keep it a a reference?

Again, I appreciate all your efforts that went into this tutorial.

[im42n8 Profile Private messageWebsite]

Twodoor55,

No, what's on the forum here is it...just something I whipped up in a word processor and copied and pasted to here. You could copy the text to Word or Wordperfect and print to a PDF output perhaps.

As we all dig into the workings of PSP trying to do some of the things we all do, we come across things sometimes that just don't make sense. So, we dig. Sometimes we come up with the answer that seems to work! That's the case here (tho I'm not sure if it's all that useful except in specialized circumstances). The math just wasn't working ... and trig is pretty straight forward (usually). So, it's a little here and a little there. Pretty soon a number of people come up with unique solutions to problems ... and we have a better understanding of how the program does what it does!

Just keep plugging!! Have fun!

Dale

[sheldonk Profile Private message]

Dale,

Thanks for posting this. Time to brush up on my trigonometry. It's only been about 30 years.

I knew there was a reason I learned that stuff! I will give it a whirl.

Sheldon